1. Field of the Invention
The present invention relates to a neck for a stringed instrument such as, e.g., a guitar or a bass-guitar and including a neck body, a fingerboard having a playing surface located adjacent to the strings, and an adjusting device located in a groove provided between the neck body and the fingerboard for adjusting the neck curvature.
2. Description of the Prior Art
An adjusting device of a type described above is disclosed in the prior European patent EP 273 372B1 of the applicant. However, it was shown that the adjusting device, which was disclosed in the above-mentioned European patent, needed improvement. The known adjusting device includes two, extending parallel to each other, bars connected at one of their ends and capable of being offset relative to each other at the other of their ends, so that the bars themselves can provide for changing the curvature of the string instrument such as guitar or bass-guitar. For the bars, comparatively large recesses need be formed in the neck which leads to weakening of the neck. Moreover, the double-bar system applies an excessive load to the neck.
Because of the foregoing drawbacks, the known adjusting device did not find wide acceptance. In accordance with one of the embodiment of the known device, only one bar is placed in the groove and is fixed at the resonance box-side anchoring point, with the end of the bar remote from the resonance box being freely arranged. The bar is held in its curved position with a curve wedge. At the free end of the wedge, there may be provided a nut which lies on the neck and which can be tightened to xe2x80x9cstraightenxe2x80x9d the bar. The object of tightening the nut was to curve the neck to the back against tensioning forces applied by the strings.
Generally, the known adjusting device should have provided the most advantageous curvature of the neck which can be corrected even after the neck has been formed and after an extensive use with different strings.
Accordingly, an object of the invention is to provide a neck for a stringed instrument, in particular a guitar or bass-guitar in which the curvature of the neck can be adjusted in a simple and precise manner after the neck has been formed and after an extensive use.
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing adjusting means including a bar secured in two, spaced from each other anchoring points provided on or in the neck and capable of absorbing tensioning or compression forces applied by the bar upon changing of its operational length, and including curve means for holding the bar in a desired curved position and for changing the operational length of the bar.
The present invention is applicable to all stringed instruments. In addition to guitars and bass-guitars, the present invention can be used in cellos, violins, double basses, concert and western guitars, banjos, etc.
The basic idea of the present invention consists in that the bar placed in the neck of a stringed instrument can transmit not only tensioning forces but also compression forces, so that the tensioning force of the strings not only can be reduced and compensated but also can be reinforced. During manufacturing, a certain curvature or reverse tensioning of the neck is provided and which, on one hand, is necessary for providing free space for oscillation of the strings with respect to the playing surface of the fingerboard and, on the other hand, prevents the strings form applying a not insignificant force which would curve the neck dependent on the strength and tensioning of the strings.
The adjusting nut according to the present invention permits to undertake correction in both directions, i.e., the effect of the tensioning force of the strings can be reinforced, reduced or compensated. A pure compensation of the string pull provides for preadjustment of the outwardly curvature in the opposite direction.
The adjusting nut according to the present invention permits to compensate manufacturing tolerances, effect of using different strings, and the change of the curvature with time.
The proposed adjusting means can be easily realized. The means according to the present invention hardly weakens the neck of a guitar or bass-guitar, rather, it reinforces the neck.
The effectiveness of the proposed adjusting means can be predetermined within certain limits by presetting the curvature radius of the groove and the radius of the curve wedge. A too flat curvature radius of the groove or the curve wedge would limit the action of the adjusting means. A too large curvature cannot be realized due to the limited material strength of the neck body and because of a limited elasticity of wood which primarily but not exclusively is used for producing the necks of stringed instruments. However, the possible, based on the neck body geometry, curvature radii of the groove or the curve wedge are adequate for achieving a desired effect.
In accordance with a common embodiment of the present invention, the curve means can be arbitrary formed. E.g., a plurality of spacers can be provided between the fingerboard and the bar. The main thing is to keep the bar in its curved position. In accordance with a preferred embodiment of the present invention, the curve means is formed as a curve wedge located between the fingerboard and the bar. In accordance with a particularly advantageous embodiment of the present invention, the curve wedge is formed of a wood piece.
The present invention is primarily based on using tensile and compression characteristic a curved tensile and compression bar. In accordance with an advantageous embodiment of the present invention, a bar, which is curved in a direction away from the playing surface of the fingerboard, is used. Theoretically, a curvature change of the curve bar in both directions, i.e., also in the direction toward the playing surface of the fingerboard, is possible. However, from the manufacturing point of view, it is very difficult to produce such a bar.
In accordance with a further advantageous embodiment of the invention the bar has at its nut-side a thread portion, and the curve means further comprises an adjusting nut screwed on the bar thread portion and fixable in the nut-side anchoring point. Here, xe2x80x9cnut-sidexe2x80x9d means in the vicinity of the free end of the neck body at which a head may or may not be arranged (in the later case, the neck is xe2x80x9cheadlessxe2x80x9d). This embodiments differs from the prior art in that the adjusting nut is fixedly secured in the anchoring point both in the tensioning and compression directions. Thereby, both compression and tensile forces can be applied to the bar.
In the resonance box-side anchoring point, the bar is fixed against both the tensile force and the compression force. Nonetheless, with corresponding expenses, means for changing the operational length of the bar, in order to achieve the same object of changing the neck curvature in both directions, can be also provided at the resonance box-side anchoring point. For completeness sake, it should be noted that the resonance box-side anchoring point can lie outside the neck, in the region of the resonance box. However, this would make the separation between the neck and the resonance box more difficult.
In a particularly preferred embodiment of the present invention, the adjusting nut is provide in its outer surface with a groove for receiving anchoring means which keeps the adjusting nut in the nut-side anchoring point, preventing it from displacement under actions of tensile and compression forces acting on the bar. However, the adjusting nut can be fixed and held in the anchoring point against tensile and compression forces by other means or in another way. However, providing anchoring means engageable in a circumferential groove provided in the adjusting nut outer surface permits to reliably hold the adjusting nut in a desired position and insures an easy access to the nut necessary for effecting the adjustment.
A particularly convenient actuation of the adjusting nut is insured when an adjusting channel is formed in the peg head adjoining the neck. It is known to provide an adjusting nuts which are used for adjusting only the action of the tensile forces. The provision of the adjusting channel in inventive means insures a convenient actuation of the adjusting nut for changing curvature parameter when both tensile and compression forces act on the bar.
Though, as discussed above, shortening or lengthening of the operational length of the bar is also possible at the resonance box-side anchoring point, it is preferred when the bar is fixed in this point.
According to a further aspect of the present invention, the bending of the neck is influenced by providing, in the resonance box-side region of the neck, reinforcing elements that provide for bending of the neck primarily in its nut-side region. This permits to provide a curvature corresponding to the oscillation characteristics of the strings. Because the fingerboard of the neck essentially retraces the amplitude characteristics of the string oscillation, it is insured that the oscillating strings are not struck, on one hand, and, on the other hand, are spaced from the fingerboard at a substantially same distance.
In accordance with an advantageous embodiment of the present invention the reinforcing elements are formed as steel inserts located in grooves provided in the neck body. They are secured in their grooves upon securing of the fingerboard to the neck.
In order to achieve the most favorable reinforcing effect, the steel inserts are so placed in their grooves that their preferential plane in the neck longitudinal direction extends transverse to the playing surface of the fingerboard. In this direction, the reinforcing of the neck against the action of the tensile forces applied by the strings is particularly effective. The curvature profile of the neck can be modified by appropriately dimensioning the thickness and length of the steel inserts.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.